Method for separating at predetermined locations a plurality of flat articles at least partly lying one on the other



United States Patent METHOD FOR SEPARATIN G AT PREDETERMINED LOCATIONS APLURALITY OF FLAT ARTICLES AT LEAST PARTLY LYING ONE ON THE OTHER WalterReist, Hinwil, Switzerland, assignor to Ferag, Fehr & Reist AG, Zurich,Switzerland No Drawing. Filed Oct. 13, 1966, Ser. No. 586,376 Claimspriority, application Austria, Oct. 21, 1965, A 9,565/ 65 8 Claims. (Cl.214-152) A very large number of objects handled in industry and in tradehave a flat shape, as, for example, paper, cardboard, pasteboard,textile fabric, felt, or synthetic plastic sheets; sheet metal or panelsof wood, plywood, synthetic plastic, or corrugated board; as well asvarious articles comprised of individual sheets folded 0r sewn orotherwise bound together. The list is exemplary, and hardly exhaustive.

During their manufacture, processing, or treatment these articles arehandled manually or by machine, and for this reason as a rule they areput in an orderly arrangement for storage or transport.

The most obvious arrangement is to have the flat objects lying at leastpartly one on the other. A pile, a series of sheets, a stack of sheetsbound together along one edge in the manner of a publication: thesealong can be considered as being the orderly arrangement envisaged,wherein the individual fiat objects lie at least partly one on theother.

When handling such stacks, particularly when handling them mechanically,the problem often arises of separating the stacks at one or morepredetermined places. Often it is neither desired nor even possible toremove the flat objects one at a time from a stack until thepredetermined place has been reached, and to form a new stack with theremoved objects. A procedure of this kind requires a relatively greatamount of time and is accompanied by various disadvantages, according tothe nature of the flat objects. For example, when removing individualmetal panels from a stack for counting, the panels can damage eachother, or in the case of thin paper sheets the latter can be crumpled.Moreover, because of the time required such a procedure is unthinkablewhen a large number of copies of a publication, such as a newspaper orperiodical, must be opened at a desired place for inserting asupplement. To solve the problem of separating a stack at apredetermined place, it has been suggested that the place be found bycounting, or measuring the thickness, down or up to the desired place,and inserting a separating element at the place thus found. However, thesupplementary equipment required for this Procedure is quite expensive,relatively difficult to set up and operate, and is insutficientlyreliable, particularly with flat objects that are not perfectly smoothor that are thin. This says nothing of the fact that in certain casesthe separating element or the equipment for counting or measuring thethickness can damage the surfaces of the flat objects.

The object of the invention is a method for separating stacks of theaforesaid kind, which method very greatly reduces the disadvantages, andentirely avoids certain of the difiiculties, set forth above.

The invention is based upon the fact that there is always a certainstatic friction between neighboring flat objects of a series of sucharticles that are at least partly lying one on top of the other.

In accordance with the invention, means are provided, either before orat the time that the stack is formed for reducing the static frictionbetween adjacent flat objects of the stack at the one or more places itis desired to separate the stack.

Several exemplary embodiments of the invention will now be described.

The object of the first embodiment is to reduce a stack of panels (sheetmetal, plywood, cardboard, or synthetic plastic, for example) of equalsize, by removing, for instance, four panels each time from the stack.When the panels are originally stacked, one surface of every fourthpanel is provided with a low-friction coating in the form of a fluid ordry lubricant which is harmless to the material of the panel. Or thesurface is made smooth, provided that this is compatible with the lateruse of the panel. Or a very low-friction sheet, such as oil paper or asheet of synthetic plastic, can be inserted between every fourth panelwhen the stack is formed.

The positions of the coating, the polished surface, or of thelow-friction sheet are not visible in the stack. These positions willhenceforth be termed low-friction positions.

If a force, parallel to the stack surface, is applied to the top panel,the four uppermost panels will move, rather than only the top panel,because the static friction between adjacent panels of this group offour panels is far greater than that between the fourth and fifthpanels. Moreover, the stack will not separate at the next lowerlow-friction position, because the static friction, in consequence ofthe four additional panels, is greater here than at the firstlow-friction position. As soon as the first four panels have thus beenshifted, the exposed surface can be engaged by conventional transportequipment and the group of four panels removed. The next four panels arenow ready for removal.

The object of the second embodiment is to open at a predetermined pageor place each of a plurality of copies of printed matter, such asperiodicals. Each copy is formed of a stack of sheets by folding or bystapling, sewing, or gluing along one edge. At least one of the twosurfaces, between which the desired place is located, is sprayed with alow-friction material, such as a dry lubricant. In the case ofnewspapers, talcum powder is a suitable lubricant. When a copy is to beopened at the desired place, a force is applied to one side of a copy ina direction approximately parallel to the sheets of the copy and havingat least a component that is not perpendicular to the folded or boundedge in the general plane of the sheets. The sheets of the copy locatedbetween the side to which the force is applied and the said desiredplace are consequently drawn back and raised, whereby a surface isexposed to enable operation of the mechanism which is necessary forfurther opening the copy. The force can be applied, for instance, bycausing the group of sheets located on one side of the desired place tomove against an abutment which engages an unbound or unfolded edge ofthe outermost sheets of the group, while continuing to advance the copya predetermined distance. The group of sheets will behave as a unit. Notonly the sheets actually held by the abutment but all of the sheets ofthe group, because of the friction between neighboring sheets, will beprevented from advancing farther, whereas the group of sheets on theother side of the desired place, because the two groups of sheets areseparated by a lubricant, are free to continue moving. In thi manner,the copy is opened at the desired place.

The object of the third embodiment is to remove a desired number ofsheets each time sheets at a time, for example) from a stack ofnormal-sized sheets of writing paper that have been blanked from a stackof the larger sheets as produced by the paper manufacturer. In carryingout this embodiment of the method, a very low friction sheet, such as asupercalendered paper of the greatest smoothness, is inserted betweenevery hundred of the larger sheets as they are stacked. Sixteennormalsized sheets may be cut from a single one of the larger sheets,for example. After the stack of larger sheets is blanked in a singleoperation, and the blanked sheets stacked, the resultingstack of sheetsis sixteen time as high as the original stack. Since the low-frictionsheets were also blanked, there is such a sheet located every onehundred sheets in the stack. To remove the sheets one hundred at a time,a lateral force is applied to one of the upper edges of the stack,causing a smooth movement of the top one-hundred sheets, While the restof the stack remains stationary and undisturbed.

The means chosen to reduce the friction depends on the kind of fiatarticles stacked and on their properties. It lies within the purview ofthe invention for the professional to choose the necessary and desirablemeans, as well as the manner of applying the force. In this connection,if the force is applied at an acute angle, rather than approximatelyparallel, to the sheet surface, the component normal to "the sheetsurface has the effect of temporarily changing the force of staticfriction between the sheet surfaces. In certain instances this can beadvantageous.

In accordance with the invention, it is sometimes necessary to lubricateor render smooth only a part of the surface of a fiat object or toinsert a low-friction sheet that covers only a part of the surfaces ofthe adjacent fiat objects, in dependence on such factors as the size ofthe fiat objects, their weight, relative smoothness or roughness oftheir surfaces, and the number of flat objects to be moved at a time.

The invention admitting of various modifications, its scope isdetermined solely by the appended claims.

I claim:

1. Method for separating at a predetermined location a plurality of fiatobjects lying at least partly one on the other to form a stack; reducingthe static friction between opposed surfaces of two adjacent flatobjects at -the loeation at which it is desired to separate the stack;

and applying to the flat objects located on one side of said location aforce having at least a component in the plane of the fiat objects, suchas to separate the stack at said location. 7

2. The method as defined in claim 1, wherein the first step includesreducing the static friction between at least a part of the area commonto the said two opposed surfaces.

3. The method as defined in claim 2, wherein the first step consists inreducing the static friction before a one of said two adjacent fiatobjects is laid on the other.

4. The method as defined in claim 3, wherein said first step consists inreducing the static friction over at least a portion of at least one ofsaid two opposed surfaces.

5. The method as defined in claim 4, wherein said first step consistsincoating at least a portion of at least one of said two opposed surfaceswith a lubricant.

6. The method as defined in claim 4, wherein said first step consists ofrendering at least a portion of at least one of said two opposedsurfaces smoother than the surfaces of the other fiat objects.

7. The method as defined in claim 3, wherein said first step consists oflaying a low-friction sheet on one of said two opposed surfaces.

8. The method as defined in claim 5, wherein said lubricant is dry.

References Cited UNITED STATES PATENTS BERNARD STICKNEY, PrimaryExaminer.

1. METHOD FOR SEPARATING AT A PREDETERMINED LOCATION A PLURALITY OF FLATOBJECTS LYING AT LEAST PARTLY ONE ON THE OTHER TO FORM A STACK; REDUCINGTHE STATIC FRICTION BETWEEN OPPOSED SURFACES OF TWO ADJACENT FLATOBJECTS AT THE LOCATION AT WHICH IT IS DESIRED TO SEPARATE THE STACK;AND APPLYING TO THE FLAT OBJECTS LOCATED ON ONE SIDE OF SAID LOCATION AFORCE HAVING AT LEAST A COMPONENT IN THE PLANE OF THE FLAT OBJECTS, SUCHAS TO SEPARATE THE STACK AT SAID LOCATION.